Accusing the West Bengal police of harassing their party workers, hundreds of CPI-M activists on Monday held a demonstration near North 24 Parnagas district's Amdanga block, where three villagers were killed over the formation of state panchayat boards last week.The Left-wing activists led by CPI-M MP Mohammad Selim and other party leaders blocked the National Highway-34, paralyzing movement of vehicles for more than an hour after being stopped by police on their way to Amdanga."Nobody had objected to our programme till yesterday, but today police stopped us from entering the villages," CPI-M leader Tanmoy Bhattacharya alleged.Three persons, including two of state ruling party Trinamool Congress and one activist of CPI-M, were killed in armed clashes at Amdanga over the formation of panchayat boards in a number of villages in the block.The Police have so far arrested 25 persons for perpetrating violence and seized a large number of crude bombs, arms and ammunition.The Left leaders on Monday accused the police of arresting and harassing their party workers.Ten people have allegedly been killed since August 25 in political clashes over the panchayat board formation in various Bengal districts.The situation in several districts has been tense over the last few days over the panchayat boards' formation after the Supreme Court permitted the notification of the results of 20,159 un-contested seats in the state panchayat polls.